1. Field of the Invention
The present invention generally relates to compliant bearing surfaces.
2. Description of Prior Art
Compliant bearing surfaces are widely used in industry. Applications range from thrust bearings in gas turbines to journal bearings in fans. Compliant bearing surfaces are often found in pressurized gas bearings. A major limitation of prior art compliant bearings is low unit load capacity. Heretofore compliant bearing technology has not been able to deal with applications involving the high pressure such as the crankshaft bearings in a combustion engine which are generally rigid insert bearings or roller bearings.
Typically a fluid lubricated bearing consists of two opposed surfaces separated by a clearance space filled with a fluid lubricant. In many applications, such as gas bearings, the clearance space can be quite small. Even in bearings with clearance spaces on the order of .001 of an inch, the machining and alignment requirements often preclude the use of a rigid bearing surface. Recently gas bearings have been invented with very high load capacity. These bearings include the supersonic bearing, Miyake et al., 4,486,105, and the Fanno line flow bearing, Dunham, pending application 07/674,790. The potential unit loads of these bearings are in the range of a several hundred pounds per square inch or more. Both of these gas bearings require controlling the cross section flow area by systematically varying the clearance gap within the bearing clearance space. The machining costs associated with contouring rigid bearing surfaces are prohibitive due to the very high accuracy required. It would be very advantageous to have a compliant bearing surface that would automatically control the gap across the clearance space of these high pressure gas bearings and which is also capable of sustaining the associated high unit loads.
Compliant bearing surfaces are also used which directly contact another bearing surface in applications such as valve seals and ball and socket joints. Generally these applications use compliant bearings made with elastic materials. However, prior art has failed to the appreciate the advantages of using compliant bearing surfaces with enclosed fluid support.
There many ingenious mechanical means in addition to compliant bearing surfaces which are employed to incorporate flexibility and self alignment into bearing systems. For example, many compliant bearings have a thin metal bearing sheet, a foil, supported by springs. Other foil designs use an elastic material to support the foil. In this type of design there is usually a trade off between compliance and stiffness. An ideal compliant bearing surface would maximize both compliance and stiffness.
It would be very desirable to have a bearing surface which approaches the ideal case of automatically conforming , is globally stiff, durable, and simple to manufacture.